Simplified and practical estimation of package cracking during reflow soldering process

Sawada, K.; Nakazawa, T.; Kawamura, Noriyasu; Matsumoto, K.; Hiruta, Y.; Sudô, Toshio

doi:10.1109/relphy.1994.307848

Cited by 28 publications

(6 citation statements)

References 8 publications

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“…Deflection z at the moment the accelerated increase of the doming begins and maximum deflection z measured immediately before the external package cracking occurred (i.e., t = t ) versus soldering shock temperature T . just before the package crack reached the surface had also been observed by other investigators (see e.g., [10], [17]). However, no interpretation was given there.…”

Section: A the Popcorn Experimentssupporting

confidence: 83%

“…Using the "wetness fraction" as discussed above and the boundary conditions at the interface as given by (14) and (15), one can calculate the concentration in the die-attach material after the preconditioning time by solving the diffusion equation (11) by the method of the Laplace transform [22] ( 16) and are the preconditioning temperature and time, respectively, , , , and . The total amount of moisture absorbed by the die-attach material during the preconditioning can be calculated from (16) by integration (17) Here is i.e., the area of the interface between MC and die-attach layer in the package. The results of the calculations, which were also performed with the "Mathcad 2000" software are: g and g for level 1 and level 2, respectively.…”

Section: ) Estimation Of Using a 1-d Modelmentioning

confidence: 99%

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On the mode II popcorn effect in thin packages

Alpern

Dudek

Schmidt

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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Experiments were carried out using P-TQFP-176 packages to study the mode II popcorn effect in thin packages. The doming of the package backside was measured as a function of time and temperature. The measurements were performed using a line projection method. An "accelerated" increase in the doming was found to correlate with the onset of the package crack propagation. It was shown that when a constant critical doming angle is reached, package cracks begin to propagate toward the surface. This critical doming angle was found to be temperature independent between 170°C and 215°C. Furthermore the development of the package doming with time was described by a simple model based on the moisture diffusion from molding compound and die-attach material in combination with a bimaterial plate theory. The water content of the die-attach layer after preconditioning was calculated from the model and it was found to be in good agreement with the results of a three dimensional finite element simulation

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Section: A the Popcorn Experimentssupporting

confidence: 83%

Section: ) Estimation Of Using a 1-d Modelmentioning

confidence: 99%

On the mode II popcorn effect in thin packages

Alpern

Dudek

Schmidt

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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show abstract

“…The moisture vaporization pressure model might be expressed in terms of temperature and moisture. The internal moisture vaporization pressure generation model given in [4] is utilized in this study. The moisture vaporization pressure model used in calculation of stresses is assumed as (11) where (MPa) is the moisture vaporization pressure, is the material constant, ( C) is temperature, and (mg/cm ) is the moisture concentration.…”

Section: Development Of Residual Stresses During Reflow Soldering mentioning

confidence: 99%

“…Residual stresses for thermosetting encapsulant packages subjected to moisture and temperature cycles are analytically evaluated based on hygro-thermo-viscoelasticity [9], [10] including the internal vaporization pressure loading [4] generated during the reflow soldering process. Hygrothermally induced stresses in a lead-on-chip (LOC) thin small outline package (TSOP) during the reflow soldering process preceded by the 168 h 85 C/85% RH moisture soaking test are analytically studied in order to assess product reliability.…”

Section: Introductionmentioning

confidence: 99%

Residual stresses in plastic IC packages during surface mounting process preceded by moisture soaking test

Goh

Yang

1997

IEEE Trans. Comp., Packag., Manufact. Technol. B

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In the present study, moisture and temperature distributions and residual stresses in plastic encapsulated integrated circuit (IC) packages are evaluated in order to assess product reliability. Finite element analyses are utilized to calculate hygro-thermally induced deformations and stresses in plastic IC packages during the surface mounting process preceded by the moisture soaking test. Residual stresses developed in thin lead-onchip (LOC) thin small outline packages (TSOP) packages during the reflow soldering process preceded by the 168 h 85 C/85% RH moisture soaking test have been studied. Numerical results showed that substantially high positive stresses z arose in the silicon chip and the leadframe while negative stresses were observed in the encapsulant below the chip when TSOP packages were exposed to the reflow soldering process. Such opposite stress development in the silicon chip and encapsulant below the chip may result in the delamination and popcorn crack. The results also showed that the magnitude of residual stresses in IC packages depended not only on the magnitude of loading but also on the loading history due to the hygro-thermo-viscoelastic behavior of plastic mold compound materials.Index Terms-Effects of moisture and temperature on plastic IC packages, hygro-thermo-viscoelastic analysis, TSOP, time dependent deformations and stresses and failures.

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“…The peak temperature of devices during this process typically ranges from 220°C and 260°C, consequently moisture stored in polymer materials vaporizes and becomes vapor pressure which cause failure of package. To predict vapor pressure, there are many calculation models in terms of different assumption [8][9][10][11][12]. However, the most widely used model is Fan's model based on micromechanics [13].…”

Section: Introductionmentioning

confidence: 99%

A numerical method on thermal-humidity behavior of electronic packaging

Mei¹,

Yao²

2011

2011 12th International Conference on Electronic Packaging Technology and High Density Packaging

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Reliability issues associated with thermal-humidity and vapor pressure have become increasingly significant for electronic devices. With the more density of the electronic packaging and the trend of lead-free material application, the film between IC and substrate will experience more harsh stress condition in the packaging process. The interface delamination is caused by these factors. Therefore, it is important to develop numerical implementation for the study of delamination mechanism. This paper presents a combined numerical methodology for predicting the thermal-humidity behavior of the process of electronic packaging. Firstly, the sequentially coupled thermal-mechanics finite element model has been applied to simulate the process of Chip on Glass (COG) packaging. Secondly, the moisture absorption and desorption have been investigated by numerical approaches. The direct concentration approach (DCA) which is able to settle the issue on the discontinuity of moisture concentration at interfaces between two materials which have distinct saturated moisture concentrations is applied in a bio-material system. Currently, commercial finite element method software such as ABAQUS is of the modulus of mass diffusion which is competent to achieve the DCA. According to the simulation, the numerical results have very good agreement with experimental data on the distribution of moisture concentrations. Further in this paper, the vapor pressure has been predicted in terms of the whole-field vapor pressure model which is put forward by Fan and the simplified Fan's vapor pressure model respectively. Compared with the results of these two models, the former one is more precise but less efficient than the latter one. At last, hygroscopic stress and thermal stress are calculated in terms of former numerical analysis and compared with the vapor pressure during the reflow process. It is reasonable to consider the vapor pressure as a major factor of failure during the reflow process by comparison.

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Simplified and practical estimation of package cracking during reflow soldering process

Cited by 28 publications

References 8 publications

On the mode II popcorn effect in thin packages

On the mode II popcorn effect in thin packages

Residual stresses in plastic IC packages during surface mounting process preceded by moisture soaking test

A numerical method on thermal-humidity behavior of electronic packaging

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